/ Home & Energy

Getting loft insulation is at the top of my to-do list

Loft insulation

Everyone knows loft insulation can make your home more energy efficient and save you money. But did you know there’s a government scheme set to expire soon, and will you plug those drafts before it’s too late?

There’s a neglected place in my home where I should spend more time, devote some money and attention. But when it’s hot and when I can find anything else to do, I keep away.

Where is this place? It’s the loft. Where a couple of decades-worth of rubbish (aka stuff-that-we-may-want-one-day) has been dumped. Most of it is squeezed around the loft hatch, and the temporary light that we’ve rigged up means that I do not dare teeter further into the dark roof space, especially as I’m likely to put my foot through a ceiling.

How can loft insulation save you money?

But I really, really should go up there because I keep thinking that insulating that loft is becoming more of a priority. We are being bombarded with messages from the government and the energy industry about how we should insulate. And loft insulation, they say, is one of the cheapest and best ways to help cut down on energy bills.

Even if you have some loft insulation already you may have less than the recommended minimum of 270mm, so it would be worth a ‘top up’.

The warnings are right. Loft insulation could help save you up to £150 a year if you don’t already have any – and there are some great deals around at the moment.

The Big Six energy companies are offering discounts with installation costs starting from around £100 and the DIY shops are charging as little as £1 per square metre for insulation. Also, if you’re over 70 or receiving certain benefits you may even get it for free.

Get in quick before the deals are gone

Too good to be true? Not really, because we’re already paying for it! A government scheme called the Carbon Emissions Reduction Target (CERT) makes us pay around £45 via our energy bills each year. This money is then used by energy companies to help provide cheaper insulation.

CERT finishes at the end of next year and so we should all get in quick while these good deals are around. And you don’t even need to use the energy company that supplies with your energy so you can shop around.

So now I’ve decided that I really, really am going to make the effort this summer. I’m preparing myself to venture up there and try and move my pile of ‘beloved mementos’.

The bin bags filled with clothes that I will never ever squeeze into again; the once hi-tech tape recorder covered in dust; and the bag of baby stuff with the expensive sheep skin which was accidently put in the tumble drier – not by me!

The benefit may be a winter where I don’t have to heat up so much fresh air and keep more heat inside my house. So it really is a win-win. Now all I have to do is fix the pole and hook so I can pull down the loft ladders and actually get up there…


Yes the article is basically correct. A well insulated loft is a good idea, it will indeed save you a small fortune in heating costs. Having a poorly insulated loft full of junk is not a good idea. Look at it this way, by having a loft full of rubbish (and that’s what most of it will be) you are effectively paying about £100 to £150 per year storage for it through higher heating costs. No brainer really, but how many people are too idle to shift that junk?
The statement of £1 per square metre might be a bit optimistic. Might be true for nasty irritating fibre glass 100mm thick but for decent non irritating thickness adding up to the recommended 270mm it’s going to cost more than £1.

Still, plenty of outfits out there doing grant supported installations for not too much money or even free for over 70’s and benefit recipiants. Just need to skip that junk.

Well Jenny insulation can be produced from all kinds of stuff and on the face of it, it seems a good idea to recycle waste materials but one must keep an eye on the economics and the final over energy and Co2 impact.
Cheapo nasty irritating insulation is made by recycling waste glass, it works.
Better stuff is made from rockwool, it works too but irritates far less.
Both are produced economically. They are not totally energy and Co2 free in thier manufacture but you normally only need the loft insulating once (if you do it right, that is 270mm plus).
Then there are things like recyled cloths, paper, substandard sheeps wool etc. etc.
They all work because insulation is basically about trapping air. But is the processing cost eco friendly? These things have to be made rot and fire proof, they have to be non-toxic and they have to be processed into a user friendly medium. The loose stuff can be real trouble. A roof needs to breath so loose lay on a windy day in a very beathable loft can end up all over the place inside and out.
No doubt some “alternative” waste products will be eco freindly and fit for purpose, but we know already the existing conventional materials are, and they’re cheap..

It’s a bit like electric transport. Sounds great, eco friendly no Co2 etc. But not if an ugly coal fired power station is making the electricity?

tom says:
25 June 2012

i dont care about your loft i just want more info on loft insulation could you do that and also answer these questions
-why loft insulation is needed
-how it reduces heat loss
-how the thickness of the loft insulation affects heat loss

I used a Which? gbest buy loose paper fibre insulation to insulate my loft and I have to agree with Chris’s comment above – it does tend to blow out of the loft when we are up there. It was also a bit of a disaster when our boiler leaked and my poor parents who were looking after our house while we were away ended up pulling arms full of sodden ex-newspaper down out of the loft. I think next time we might go for something a bit easier to deal with if anything goes wrong – but id does provide brilliant insulation.

Dave says:
5 June 2011

We installed extra loft insullation 2 years ago- increasing from 100mmm to 300mm!
So far the house does not feel warmer but this may be due to the two bad winters.Because of the latter and having water tanks in the loft( appropriately insulated) we felt obliged to partially open the loft hatch at night during the worst of the Artic conditions! Better to be cool and dry rather than frozen and wet!

Well Dave, if you have thermostatically controlled heating the house won’t feel any different because soon as you reach the set temperature the heating goes off. But because you are better insulated you should be buying less gas, or whatever, to maintain that set temperature.
Check you bills (units rather than price, price seems to be forever going up)
As for the tanks in the loft, you realise you’re supposed to not insulate beneath them? That way some of the warmth in the house can escape through the ceiling to prevent any water freezing in the tank, but do remember to insulate all the pipework, both hot and cold.
If you do this there will be no need to leave the hatch open, or therfore to have that arctic cold air downward blast through the hatch undoing all your good insulating work
You can be both warm and dry, if you do it right.

I have had my loft insulated free to the max depth . I now find, as does another Architect friend, that in summer the house is colder than outside because the suns’ heat is not getting into it, and am having to put the heating on in the evening (in June!!) which I never had to do before.
This of course increases my heating bills.

So Alan you are suggesting that insulating your loft has increased your energy bills because summer heat is not warming the fabric of your house?
Are you suggesting that Winter heat positive gain through insulation is less than Summer heat negative gain?
If your house feels cooler in the summer try opening a window, let the warmth in that way.

All in all you being an Architect or not don’t think many would agree with your argument.

If you read my comment again you will see we have to put the heating on in the evening (In June) because its cold – so no point in opening the windows to let heat in then. What I am saying is that we hardly ever had to put the heating on in June before the insulation was increased.
I am talking about Glasgow area -perhaps you live in the South?

No Alan I think you misunderstand me.
Before you insulated the fabric of your house was warmed during the day, summer daytime temperatures, sunlight etc. This warmth then got released during the evening.
Now you’re insulated not so much daytime warmth is being absorbed by the house so you find on some summer evenings you need some heating on.
However if during the daytime it’s warmer outside than in you might compensate by opening windows to allow the fabric of the house to absorb some of that heat. Just like it did before you insulated.
In the evening you close the windows and benefit from the daytime absorbed warmth, again just like you did before insulating.
But now however because you are better insulated that warmth is retained within the house better.

Chris There is no way heat entering the house from open windows and doors (which of course we do leave open anyway) in the summer could match the heat gained from direct sunlight on an (uninsulated) roof/loft.
I am serious about this post as I think money is being wasted on Government insulation provision, as it is not reducing heating bills in the way intended.
What we need is a comment from an unbiased heating specialist-is there anybody out there?

Sim1234 says:
27 July 2011

This article just proves the mistake in your “no selling at smart meter install campaign”. You say yourself that you know that you should have your loft insulated, it will keep you warmer and save money etc etc but the point is that in spite of this (and being in a job where you should have!) you still haven’t acted on this for a long time, and may not have yet still. This is the situation for everyone, insulation is boring and even if we know the facts we never get round to doing anything about it because we are not interested and have better, more interesting, things to do – in the meantime all that money is spent on heating the sky! This is the problem with saying no selling. These products need to be sold or we never get around to doing anything about them and having a smart meter installed is probably one of the few times any of us will be seriously thinking about energy conservation. Keep the campaign for proper miss-selling and encourage installation of insulation measures.

Hi Sim1234 – I think, if anything, the opposite is true. Having a smart meter would give someone a much more immediate and real indication of how much was being spent on ‘heating the sky’ (I like that phrase =). By getting a detailed breakdown of the energy they’re using, and how much it is costing them on a daily basis, more people might be able to work out the cost-benefit of having insulation. At the moment people know it’ll save them money, but do they really know how much? It’s hard to tell, especially given that tariffs are so complex.

I do think you’re right, though, that people will need more information about energy saving measures. Once they start thinking about energy consumption and considering where best to invest to make their property greener, there’ll be a real call for decent information and advice about how to e.g. insulate your home to get the most for your money.

But the smart meter ‘no selling’ challenge isn’t about preventing people from getting this information – it’s about preventing energy companies from giving you what amounts to a compulsory sales chat during a home visit you may not even want. Energy companies sending you info or leaving a leaflet after your installation? Fine. Companies asking you if you’d like an energy consultation? Fine. Sending salesmen into your house when you’re expecting an installer and making you listen to a spiel you didn’t ask for? Definitely not fine. Given that our research shows 93% of people say they wouldn’t let an energy company salesperson into their home, we think it’s cheeky to send them in without warning customers, or asking for permission.

Sim1234 says:
27 July 2011

The problem with your argument over more informed consumers taking action when they want to isn’t supported by real life experience. Can you tell me why people working at Which?, in the Energy team, who have all the infomation on costs and savings available to them, the professional interest to do something about getting better insulation and the know how to access the resources, freely admit to not having done anything about it for a long time? If you haven’t bothered then the likelihood of a busy person without this interest doing it is minimal. Like it or not, these products are very low interest and need to be sold, most consumers will not act on their own initiative.

That’s a bit unfair, Sim – we all have good intentions but not all of us get round to it. I see your point that someone on the energy team is pretty well informed about the benefits of insulation, but the fact remains that we’re all human beings with many different competing pressures.

I also have to disagree on your comment that ‘most consumers will not act on their own initiative.’ At Which? we assume they do, which is why we provide information and advice for people looking for products! I definitely wouldn’t agree that consumers need in-home salespeople to ‘help’ them make the right decision – on the contrary, I think a much more informed and considered opinion is likely to be made by looking at the internet, and independent sources of information. I’d never say that products ‘need to be sold’ to consumers who don’t understand what their benefits might be.

Sim1234 says:
28 July 2011

Don’t think I’m being unfair at all, it just proves my point. No-one is interested in insulation and they are not going to go on the internet to make a considered, well informed purchase. The only logical outcome of your campaign is that less insulation gets installed. That is bad news for the consumers you claim to represent, as they continue to waste money and live in cold houses, and bad news for carbon emissions and the environment. Which? are taking the same approach to this as you would to buying a televisions, cars or a holiday – you need to accept that consumers behave differently with different products and modify your approach.

ccmrowe says:
5 October 2011

Over a month ago, I purchased 5 rolls of the economy (£3) insulation from B and Q and manufactured by Knauf. As I was laying one roll I could see that one section of it was actually melting in front of my eyes (yes melting!), I got in touch with the manufacturers and they came to collect a sample for testing. That was a month ago and I keep chasing them for a reply. In the meantime, if you’ve purchased this insulation recently I’d strongly suggest that you check your loft!
E-mail my if you want photos!

that sounds suspicious.. they probably haven’t provided you with any results as they do not know… unfortunately everything has a problem somewhere.. the only thing i can think of is that your loft was too hot, therefor melting the fabric… you should check some websites out that talk about the potential worries of loft insulation… also… could you e-mail me the pictures, it sounds weird…

i like insulation it good for the inviroment

you know.. you all sound pretty knowledgeable on this topic of heat loss via the loft.. but none of you ever agree on the same thing… in my opinion loft insulation is installed to reduce heat bills.. (which in most cases it does) and help reduce convection in your roof from stealing your heat… i am trying to do some coursework via this website… but it is impossible with everyone’s counter arguments, it would be nice if you all just agreed on one statement.. Thanks – John

and.. a lot of you seem to disagree with factual comments… that tend to make sense… having an opinion is good.. but disagreeing on everyone’s view is a bit biased of your own views…

Emmie says:
25 January 2013

I agree with tom, answer those questions, i obviously have the same science project as him.

Peter says:
14 August 2016

None of these types of report ever mention that I summer your house will boil and you will overheat. It happened to us and just do an Internet search and you see it’s s common problem. Sealing up a house and trapping heat in just makes summer unbearable. These ‘experts’ don’t understand about being comfortable.

I don’t think you are correct Peter in blaming the insulation for any overheating problem. In fact if you look at earlier comments you will see someone saying the precise opposite.

The problem I am sure is a lack of ventilation and the serious amount of solar gain from sunshine which has become prevalent with larger and larger windows being fitted. In early spring with my handheld infra-red thermometer [around £14] I have walls inside which the sun has raised to temperatures in the 20’s. Some of my windows are 6X8 feet so very large areas are being heated.

In Australia they understand solar gain very well and market solar defeating blinds. In Europe they use shutters and awnings to prevent heat build-up.

To compound the problem a lot of UK houses are being built to minimise draughts from the building and we as a race are not very good at opening windows in the early morning to get fresh cool air each day into the house. This cooler air and shading rooms with curtains and blinds may make a considerable difference.

Insulation cannot make your house overheat. It’s a physical impossibility – the laws of thermodynamics don’t allow it. All insulation does is reduce heat loss from the house. There are reasons who you might assume the house is overheating, but they’re nothing whatsoever to do with the insulation.

Simple strategy for keeping your house (relatively) cool in very hot weather:

1 Keep the upstairs (and any safe downstairs) windows open overnight.
2. Keep an eye on the inside and outside temperatures. When the temperature outside is within one degree of the inside temperature close all the windows.
3. Work out which area of the house gets the most sunlight and lock that off (if you can) during the hot hours.
4. Open all the windows when the outside temperature drops below the inside.
5. Grab a large bottle of whiskey and lie in the shade outside.

When the house gets too hot in the summer we open some windows. In the Middle East, old houses without air conditioning have a central roof tower that creates a cooling air flow.

I worked in a Dental Surgery with minimal upstairs heating. (The downstairs surgery space was heated) I can assure you that after the loft insulation was upgraded the upstairs was very very much warmer in the cooler months. On the rare occasions in the UK when it was very hot it was certainly warmer upstairs. Nothing that opening the windows couldn’t solve and lets face it a pretty rare occurrence in the UK. I’m really not sure how anyone thinks proper loft insulation can be a bad idea!

At my last house, I got free fibre insulation (from EDF) to top up my loft. I didn’t use the loft for storage and savings were noticeable. My current house is smaller and I need the loft storage space. The existing insulation is too thin (mineral wool). To avoid paying for a raised loft floor resulting in reduced head height, the quickest and cheaper option is to use a polyisocyanurate board. This only needs to be about a quarter of the depth of fibre (70 mm) for the same insulation properties. The boards are easily cut with a bread knife to fit between the ceiling joists and do not protrude above them so boards can be fixed directly to the ceiling joists. The boards are foil faced which leads to increased comfort from reflected radiated heat. Many “experts” and government subsidy schemes only think of convected heat and overlook the savings and increased comfort from radiated heat. The grants/subsidy system has been pathetic for far too many years. Infra red aerial surveys mean that government and local authorities know exactly which properties are poorly insulated. Grants are often means tested and installations fragmented. It involves very significant cost savings to install insulation in a whole terrace or houses in a particular road than the current piecemeal system. The environment doesn’t care if you are rich or poor. The same applies to cavity wall insulation. Local authorities know which houses have them and (provided that they a planning archive) can tell what thickness the cavity is. Regarding current policies, businesses have benefited disproportionately to domestic properties yet the government know that the UK will miss its carbon reduction target unless the domestic housing stock is better insulated. The government must at least try to get more “bang for the buck” and that means instigating neighbourhood schemes. It also means changing to a “no exceptions” to the “decent housing” scheme whereas currently, local authorities and housing associations are allowed to fail on one criteria.

Loft Boarding Insulation says:
28 April 2021

This article is full of  valuable detail! The smallest changes have the largest impact.

Loft and Insulation says:
28 April 2021

Wow. Nice post. Thank you.

Loft and Insulation says:
15 October 2021

Nice article! Looking forward to more ideas.